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A retrieval methodology based on the Bayesian neural network (BNN) is presented that inverts the ice water path (IWP), mean mass-weighted diameter ( $D_{\mathrm {me}}$ ), and cloud height of ice clouds from submillimeter radiometer observations. The training dataset was created using collecting cloud profiles from the DARDAR (raDAR/liDAR) database and running simulations by the atmospheric radiative transfer simulator (ARTS) model. Since the effective radius ( $r_{e}$ ) is the size descriptor of ice particles in the DARDAR database, a lookup table of ice water content (IWC), $D_{\mathrm {me}}$ , and $r_{e}$ was constructed to convert $r_{e}$ profiles into $D_{\mathrm {me}}$ profiles. In addition, random noises corresponding to the measurement uncertainties of the compact scanning submillimeter-wave imaging radiometer (CoSSIR) during the TC4 experiment were added to the simulated brightness temperatures before training the BNN. The proposed retrieval method was first applied to the simulated testing database and then to the observations of CoSSIR. Moreover, the retrieved IWP and $D_{\mathrm {me}}$ were compared to the retrievals of the Bayesian Monte Carlo integration (BMCI) method. The retrieved cloud height was assessed by cloud height extracted from the reflectivity data of the cloud radar system (CPS) flow on the same aircraft with CoSSIR. The comparison showed that the correlation coefficients of the retrieved IWP and $D_{\mathrm {me}}$ from the two methods are above 0.8, and the retrieved cloud height also showed good agreement with that extracted from the CPS.

In order to improve the design of PSA system for fuel cell hydrogen production, a non-isothermal model of eight-bed PSA hydrogen process with five-component (H2/N2/CH4/CO/CO2 = 74.59%/0.01%/4.2%/2.5%/18.7% (vol)) four-stage pressure equalization was developed in this article. The model adopts a composite adsorption bed of activated carbon and zeolite 5A. In this article, pressure variation, temperature field and separation performance are stimulated, and also effect of providing purge (PP) differential pressure and the ratio of activated carbon to zeolite 5A on separation performance in the process of producing industrial hydrogen (CO content in hydrogen is 10 µl·L−1) and fuel cell hydrogen (CO content is 0.2 µl·L−1) are compared. The results show that Run 3, when the CO content in hydrogen is 10 µl·L−1, the hydrogen recovery is 89.8%, and the average flow rate of feed gas is 0.529 mol·s−1; When the CO content in hydrogen is 0.2 µl·L−1, the hydrogen recovery is 85.2%, and the average flow rate of feed gas is 0.43 mol·s−1. With the increase of PP differential pressure, hydrogen recovery first increases and then decreases, reaching the maximum when PP differential pressure is 0.263 MPa; With the decrease of the ratio of activated carbon to zeolite 5A, the hydrogen recovery increases gradually. When the CO content in hydrogen is 0.2 µl·L−1the hydrogen recovery increases more obviously, from 83.96% to 86.37%, until the ratio of activated carbon to zeolite 5A decreases to 1. At the end of PP step, no large amount of CO2in gas or solid phase enters the zeolite 5A adsorption bed, while when the CO content in hydrogen is 10 µl·L−1, and the ratio of carbon to zeolite 5A is less than 1.4, more CO2will enter the zeolite 5A bed.

The phase state information of cloud water is important for the airborne measurement of the microphysical properties of a cloud. A cloud particle detection system based on polarization detection, which can be used to detect the size and phase state of cloud particles for particle diameters of less than 50 µm, was developed by detecting the energy of the forward scattering and the depolarization of backscattered light. The sensitive area was calculated through the width and depth of the field of view of the laser beam. The system was calibrated using standard particles. The response curve of the system to the cloud particles was obtained by calculating the relationship between the standard particles and the cloud droplets. Finally, the liquid droplets and typical nonspherical particles were measured, and the results compared with a simulation. The comparison results indicated that the system could detect spherical and nonspherical cloud particles and could discriminate between nonspherical cloud particles and liquid droplets.

Data from the Cloud Imaging and Particle Size experiment on the Aeronomy of Ice in the Mesosphere (AIM) satellite are employed to study the impact of small‐scale gravity wave (GW) on albedo, ice water content (IWC), and particle radius (PR) of polar mesospheric clouds. Overall, 23,987 eligible GW events, with a horizontal wavelength of 20–150 km are eventually extracted from Cloud Imaging and Particle Size level 2 orbit albedo maps during 2007–2011. The overall statistical results show that when small‐scale GWs travel horizontally in polar mesospheric clouds, they can amplify the albedo and IWC by a rate of 10.0–22.6%, while reducing the PR by as much as −7.01%. Owing to the strong temporal and spatial dependences, the albedo and IWC variations are larger on an average during the core of the season, while they decrease during the initial and final periods of the season. The obvious zonal asymmetries are also found. The albedo variations show a positive linear relation with the GW amplitudes in albedo, as opposed to a negative linear relation with GW horizontal wavelengths. In most of the GW events, the periodic variation in the trend of albedo exhibits an anticorrelation with that of PR. Combining previous research studies with our results, we deduce that the rapid change in particle concentration and the upward movement of water vapor by GWs may be very important aspects for explaining the influence mechanism. Small‐scale GWs can amplify the PMC albedo and IWC, while reducing PR temporarily, on an averageAlbedo, IWC, and PR variations are dependent on the latitude, longitude, and DFSAlbedo variations show a linear relationship with GW amplitude and horizontal wavelength

A waveguide-coupled surface phonon resonance (SPhR) sensor with super-resolution based on Fano resonance (FR) by using a multilayer system within the Kretschmann configuration in the mid-infrared wavelength region is proposed. Due to the coherent interference of the waveguide and the surface phonon polariton modes, the calculated reflectivity spectrum possesses sharp asymmetric FR dips. An ultra-small linewidth is formed because of the Fano coupling, and the physical features contribute to a highly efficient nano-sensor for refractive index sensing. The bulk and surface sensitivity by intensities are greatly enhanced relative to those of conventional SPhR sensors.

A sporadic case of noctilucent clouds (NLCs) was observed unexpectedly on the night of the 6–7 July 2020 in Beijing (40°2′N, 115°30′E). The noticeable wavy structures and observed ambient temperature (135.54K at the mesosphere and lower thermosphere [MLT]), both indicated that the increase in temperature oscillations could be the cold phase of gravity waves (GWs). The reasons for NLC formation were analyzed based on the observations and model data sets in our study. The real‐time synoptic analysis revealed that there were GWs originally generated by a squall line in the troposphere. Due to the blocked effect of a stable tropopause inversion layer (TIL), the GWs broke, leading to strong energy dissipation near the TIL. The reverse ray tracing analysis between the TIL and NLCs' layer revealed the travel distance (206.88 km) and time (49.91 min) of GWs. These findings show that the turbulence over the TIL (at approximately 14.64 km) excited secondary GWs, which propagated upwards toward the mesosphere and probably interacted with diurnal and semi‐diurnal tides. The cold phase of the larger‐amplitude waves can provide optimal conditions for NLCs forming. Our study highlights the significance of dynamic coupling mechanisms regarding the effects from troposphere to MLT thermal conditions and offers a case study for the increasing occurrences of NLCs at midlatitudes. Noctilucent clouds (NLCs) are ice clouds forming at 80–86 km during summertime in the Northern Hemisphere. During the night of 6–7 July 2020, a Chinese photographer captured the occurrence of NLCs in Beijing (40°2′N, 115°30′E). The wavy structures in the photographs revealed that the occurrence of NLCs had a close relation with the atmospheric gravity waves (GWs), the significant transport of momentum and energy in the atmosphere. We used comprehensive data sets and models to locate the source of these GWs. The real‐time synoptic analysis in the troposphere revealed that the GWs were generated by a convective system, a squall line. However, a stable tropopause inversion layer inhibited the waves like a huge lid, resulting in strong energy dissipation and exciting new GWs propagating upwards. The secondary‐generation GWs can interact with large‐scale waves and cause severe cooling in the MLT, providing an ideal condition for the growth of ice particles in NLCs. These particles integrated the wave source at the tropopause and GWs that are visible in the NLCs for the first time at midlatitudes. The results inspired us to further explore the connection between the troposphere and the upper atmosphere in the future studies. The mechanism of a sporadic case of formation of midlatitude noctilucent clouds (NLCs) in China is demonstratedThe interaction between gravity waves (GWs) and tidal waves substantially cooled the NLC layerTurbulence of the tropopause inversion layer excited secondary GWs which propagated upwards toward the mesosphere The mechanism of a sporadic case of formation of midlatitude noctilucent clouds (NLCs) in China is demonstrated The interaction between gravity waves (GWs) and tidal waves substantially cooled the NLC layer Turbulence of the tropopause inversion layer excited secondary GWs which propagated upwards toward the mesosphere

A micro-pulse LIDAR system (MPL) was employed to measure the aerosol over Pudong, Shanghai from July 2008 to January 2009. Based on Fernald method, aerosol optical variables such as extinction coefficient were retrieved and analyzed. Results show that aerosol exists mainly in low layers; aerosol loading reaches its maximum in the afternoon, and then decreases with time until its minimum at night. Most of the aerosol concentrates in the layer below 3 km, and optical extinction coefficient in the layer below 2 km contributes 84.25% of that below 6 km. Two extinction coefficient peaks appear in the near surface layer up to 500 m and in the level around 1000 m. Aerosol extinction coefficient shows a seasonal downward trend from summer to winter.

Oceans are widely regarded as major offsets for anthropogenic carbon emissions, leading to an evident lower measured atmospheric CO2concentration than expected. It is thus of great significance to develop effective means to monitor CO2fluxes over oceans globally. In this work, we utilized observations obtained by an airborne CO2‐IPDA LIDAR to evaluate the potential of such means in estimating sea‐air CO2flux. During a flight experiment in 2019, we have estimated the CO2exchange rate, −1.5 ± 0.18 mmol/m2/h, between the Bohai Bay and the atmosphere using equilibrium atmospheric boundary layer theory. These findings indicated that the forthcoming space‐borne CO2‐IPDA LIDAR is capable of identifying CO2uptakes over oceans qualitatively, which would be a novel means and a basis for monitoring CO2fluxes over global oceans. Oceans are regarded as important offsets to anthropogenic CO2emissions, delaying an increase in atmospheric CO2concentration. However, there is a lack of understanding of the intensity, distribution, and variability of marine carbon sinks. China is due to launch a space‐borne LIDAR for measuring atmospheric CO2concentration globally in 2021. In this work, we utilized data collected during a flight test for the forthcoming satellite mission to explore the ability of such a novel means in revealing and estimating CO2fluxes of oceans quantitatively. Results confirmed an evident CO2uptake in the Bohai Bay and exhibited a promising prospect for the novel CO2measuring means. We detected XCO2gradient during a flight campaign in ChinaRetrieve XCO2in the atmosphere boundary layer by cloud slicing methodProvide a model to retrieve CO2flux over ocean by CO2‐IPDA system We detected XCO2gradient during a flight campaign in China Retrieve XCO2in the atmosphere boundary layer by cloud slicing method Provide a model to retrieve CO2flux over ocean by CO2‐IPDA system

An enhanced absorption of monolayer graphene is obtained in a multilayer film-based attenuated total reflectance configuration in the visible wavelength range. The enhanced absorption under transverse magnetic and electric conditions is associated with the excitation of the waveguide mode in the thin-film layer, which is verified by the numerical calculation of field profiles. The obtained results manifest that the model induces a high field enhancement at the graphene-dielectric interface with the resonant angle, which implies potential sensing applications. The magnitude of the figure of merit is found to be three times higher than that of a conventional surface plasmon sensor.